A wheel alignment examining apparatus for examining the mounting condition of a wheel of a vehicle, such as an automobile, is well known in the art. Various parameters are set for a wheel mounted on a vehicle, such as an automobile that include the so-called wheel inclination parameters, such as toe, camber and castor, in relation to running performance. In order for a vehicle to have an excellent running performance, it is important that such wheel inclination parameters be set and maintained at proper values. These wheel inclination parameters are checked before a vehicle is sent to the market upon its completion, and also checked after repair of a vehicle, such as replacement of the wheels.
It is often desired that the steering radii of a motor vehicle be tested and set before being sent to the marketplace. The front wheels of the motor vehicle are tested for a predetermined degree of turning with respect to the motor vehicle. Such tests are completed in a static mode where the wheels of the motor vehicles do not rotate during testing. To test the dynamic performance of the motor vehicle, the wheels of the motor vehicle must be allowed to rotate freely while on the motor vehicle in order to properly simulate the normal operating conditions of the motor vehicle. It is known to support each wheel of the motor vehicle on a pair of cylindrical rollers wherein the wheels of the motor vehicle are rotated while keeping the motor vehicle in a stationary position. The cylindrical rollers are typically driven by their own independent motors or drives.
The cylindrical rollers may be supported on a float plate which utilizes ball bearings on the bottom of the float plate to allow the float plate to move along a substantially flat horizontal surface and allow the motor vehicle to settle into a natural position for rotational movement of the motor vehicle's wheels. Thus, the cylindrical rollers which support the wheels of the motor vehicle are mounted to the float plates. It would be desirable to provide another means to allow the float plate to move along the flat horizontal surface which eliminates the use of ball bearings and the required bearing surface made of hardened material that support the ball bearings. The ball bearings and hardened bearing surface are additional components that require cleaning and lubrication. It would also be desirable to provide a float plate which rotates to allow for the testing of the motor vehicle's turning radius, while also providing for the floating feature of the float plate.
In addition, once the dynamic testing of the motor vehicle has been completed, the motor vehicles are driven off the cylindrical rollers and ramps that are provided at the test site. Since the rollers are free rolling, the rollers and float plates must somehow be locked in order that the wheels of the motor vehicle do not spin on the cylindrical rollers. Several known designs have attempted to utilize brakes by which to lock the cylindrical rollers and prevent the cylindrical rollers from rotating. Such brake designs typically wear, thus requiring constant adjustment. In addition, other brakes utilize bands which break under excessive forces.
Other designs have provided lock mechanisms to lock the cylindrical rollers. The tires of the motor vehicle sit low within the valley formed between the two cylindrical rollers, thus, when the motor vehicle is driven off the rollers, a great amount of force is applied to the braking mechanisms. Such high forces create excessive brake wear and slipping of brakes as well as the constant need for adjustment.
Therefore, it would be desirable to provide a locking mechanism which lifted the vehicles partially or completely off the rollers so as to reduce the amount of pressure applied to the braking mechanisms. It would also be desirable to provide a locking mechanism which did not require continual adjustment over the life of the brake pad. Further, it would be desirable to provide a locking mechanism that locks both the cylindrical rollers and the float plate with the same apparatus.